When Margaret Thatcher and Ronald Reagan were leading their countries in new directions during their respective terms in office, it was the strongest transatlantic partnership since the second world war – for, however much they differed in style, they shared the same vision.

She was the feisty prime minister, a strong-willed and articulate contrarian. He was equally strong-willed, but in the more accommodating cloak of an Irish-American storyteller who was perfectly cast as president. For the movie, think Katherine Hepburn and Spencer Tracy (or the magical Meryl Streep for both roles).

Together, Baroness Thatcher and Ronald Reagan championed fewer government entitlements, less regulation, a more robust free market economy, British and American exceptionalism, and a foreign policy that had, as its unofficial motto, "might is right".

They were a formidable pair, each reinforcing the other at every opportunity. President Reagan was so fond of her I sometimes thought he was tempted to give her a White House telephone extension.

It seems to me their most enduring joint legacy was the handling of Mikhail Gorbachev as the Soviet Union was beginning to unravel. When Prime Minister Thatcher said of Gorbachev, "We can do business together," it gave President Reagan some cover with the American right wing which was deeply suspicious of doing deals with Moscow.

When Reagan left office, Thatcher had a cordial but different relationship with his successor, George HW Bush. She was sharply critical of the decision not to pursue Saddam Hussein all the way to Baghdad during the first Gulf war.

She also differed with the new president on whether Germany should be re-united following the fall of the Berlin Wall. Her argument against re-unification put her on the wrong side of history.

Ironically, a unified Germany is now headed by a woman, Angela Merkel, who shares Thatcher's economic philosophy and who, like Prime Minister Thatcher, once worked as a chemist in a laboratory.

Personally, as a journalist, I will miss Baroness Thatcher's powerful presence. One of my fondest memories was an annual invitation I shared with three of my prominent colleagues during her visits to New York. We'd be aligned across from her at a breakfast table for a vigorous discussion of the issues of the day.

One by one, she would whack our preambles, as if we were a line-up of soft-boiled eggs meant to be eaten, not indulged.